In recent years, the feature of multiplexing optical signals is being rapidly promoted. For example, in terms of time domains, optical signal channels, the number of which is approximately 10 to 100, are multiplexed, and an optical transmission rate comes close to a level of 100 Gb/s to several Tb/s. Moreover, attention is also being focused on coherent optical transmission systems such as optical Phase Shift Keying (optical PSK) and optical Quadrature Amplitude Modulation (optical QAM), and on complicated optical multiplicity systems such as optical Orthogonal Frequency Division Multiplexing (optical OFDM) and Optical Code Division Multiplexing (optical OCDM).
Incidentally, with respect to existing optical measurement devices, a practical technique for collectively analyzing and evaluating, for example, a high-speed signal having high optical multiplicity, an optical multiplex signal and a coherent signal, such as those described above, is not established. For example, the conventional wideband optical measurement devices depend on complicated all-optical signal processing techniques based on Second Harmonic wave Generation (SHG), a Four-Wave Mixing (FWM) phenomenon and the like, and therefore it is difficult to practically apply an optical communication network to the conventional wideband optical measurement devices. In addition, analyzing a single channel signal is the best the conventional optical measurement devices can do from a functional point of view as well. Therefore, the conventional optical measurement devices are not suitable for the analysis of an optical multiplex signal that has been highly multi-dimensionally multiplexed on an optical communication network.